The present invention relates generally to apparatus and methods for monitoring the operation of rotating machines, such as compressors and pumps in heating, ventilation and air conditioning systems. In particular, the invention relates to apparatus and methods that monitor vibration of such rotating machines.
Rotating machines have a wide variety of applications. For example, motors drive compressors and pumps in heating, ventilation and air conditioning (HVAC) systems found in most buildings. Inevitably such machinery develops various mechanical problems with time. Bearings wear, cracks and other deformations develop, and the rotating components become unbalanced. Initially such faults merely reduce the efficiency and performance of the machine. However, if not remedied in time, the faults can progress in magnitude to a point at which the machine fails to operate or causes damage to other components. A relatively inexpensive and simple repair if made early in the fault progression can prevent more serious and expensive subsequent repairs.
Therefore, it is desirable to detect and locate malfunctioning components as early as possible. In addition, it is desirable to detect such faults without interfering with normal machine operation. Taking a machine out of service to perform diagnostic operations may be undesirable and inefficient. Furthermore, the onset of many defects often is not apparent without extensively dismantling the machine. Accordingly, it would be advantageous to provide a system that is capable of continuously monitoring machines and automatically diagnosing faults without interfering with the normal operational procedures.
Fault analysis of rotating machinery is based on interpreting specific data values. For vibration analysis, these values may include peaks of the frequency spectrum, the energy over a specified frequency band, or a direct input value, such as the operating load of the machine at the time when the measurements were made. FIG. 4 illustrates some of these values, including peaks in the frequency spectrum. Vibrations produced by rotating machinery are a result of the physical characteristics of a particular machine. Consequently, the extraction of fundamental frequencies and their amplitudes for various components is important in determining the condition of a machine. The amplitudes of the vibrations produced and the combination of different vibrations can be interpreted to determine the condition of a machine. Furthermore, since numerous machines have the same physical characteristic (i.e., the same manufacturer and model), they often are expected to produce similar vibrations. Therefore, information about a first machine may be useful in analyzing a second machine.
Accordingly, it would be advantageous to provide a system that allows an end-user to create general templates that capture the analytical knowledge of the user as well as incorporate vibration spectra collected from instrumentation of various machines in order to serve as a basis for an overall vibration analysis. In addition, since vibration analysis can often be quite complex, it would also be advantageous to provide an effective method of defining, organizing, and arranging rules and templates used in the overall vibration analysis.